Placebo matching IV afimkibart. Placebo matching SC afimkibart.

Percentage of participants achieving a decrease in SES-CD of >=50% from baseline. The SES-CD is a composite of four features of endoscopic activity (presence and size of ulcers, extent of ulcerated surface, extent of affected and presence and type of narrowings or stenosis) in up to five ileocolonic segments (terminal ileum, right colon, transverse colon, sigmoid and left colon, and rectum). Each feature is scored on a scale from 0 to 3, giving segment subscores of 0 to 12 points and a total SES-CD range of 0-60, with a higher value indicating greater severity.

Percentage of participants with the daily number of liquid or very soft stools <=2.8 and the average of daily abdominal pain scores in the past week <=1, with neither being greater than baseline.

Percentage of participants with an SES-CD of 0 to 4 with a decrease from baseline >=2 and no subscore >1.

Percentage of participants with an SES-CD ulcerated surface subscore of 0.

Daily average number of liquid or very soft stools over 7 days.

The average daily rating of abdominal pain in the past 7 days. The pain is assessed on a scale of 0-3 with 0 indicating no pain and 3 indicating severe pain.

Percentage of participants with SES-CD=0 to 4 with decrease from baseline >=2 and no subscore >1 .

Percentage of participants with the daily number of liquid or very soft stools <=2.8 and the average of daily abdominal pain scores in the past week <=1, with neither being greater than baseline.

Percentage of participants with clinical remission at Week 52 and no use of corticosteroids for CD at least 8 weeks prior to Week 52.

Percentage of participants with clinical remission at both Weeks 12 and 52.

Percentage of participants with endoscopic response at both Weeks 12 and 52.

Percentage of participants achieving a CDAI score of <150 and SES-CD of 0 to 4 with a decrease from baseline >=2 and no subscore >1 at Week 52.

Percentage of participants with an SES-CD ulcerated surface subscore of 0.

Bowel urgency from baseline through week 12 and week 52. Bowel urgency is a single-item self-reported assessment of sudden or immediate need to have a bowel movement in the past 24 hours. The item response is reported on a 4-point Likert scale, from "None" to "Severe."

Fatigue, as measured by the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), from baseline to Week 12 and Week 52. FACIT-F is a 13-item self-reported assessment of fatigue. Each item response option indicates the degree to which a given statement describing the level or impact of fatigue applies in the past 7 days. Response options are graded on a 5-point Likert-type scale, from "Not at all" to "Very much."

Change in IBDQ score from baseline to week 12 and 52. The IBDQ is a 32-item questionnaire that measures four domains: bowel symptoms (10 questions); systemic symptoms (5 questions); emotional function (12 questions); and social function (5 questions). The total score ranges from 32-224, with a higher score indicating a better quality of life.

Percentage of participants achieving a CDAI score of <150 at Week 12 in biomarker-defined subgroups. The index is a weighted sum of scores on eight components: number of liquid or soft stools (stool frequency), abdominal pain, general well-being, number of complications, use of anti-diarrheal medication, presence of an abdominal mass, hematocrit, and percentage deviation from standard body weight. CDAI generally ranges from 0 to roughly 600, with higher values indicating greater activity.

Percentage of participants achieving a CDAI score of <150 at Week 52 in biomarker-defined subgroups. The index is a weighted sum of scores on eight components: number of liquid or soft stools (stool frequency), abdominal pain, general well-being, number of complications, use of anti-diarrheal medication, presence of an abdominal mass, hematocrit, and percentage deviation from standard body weight. CDAI generally ranges from 0 to roughly 600, with higher values indicating greater activity.

Percentage of participants achieving a decrease in SES-CD of >=50% from baseline. The SES-CD is a composite of four features of endoscopic activity (presence and size of ulcers, extent of ulcerated surface, extent of affected and presence and type of narrowings or stenosis) in up to five ileocolonic segments (terminal ileum, right colon, transverse colon, sigmoid and left colon, and rectum). Each feature is scored on a scale from 0 to 3, giving segment subscores of 0 to 12 points and a total SES-CD range of 0-60, with a higher value indicating greater severity.

Percentage of participants achieving a decrease in SES-CD of >=50% from baseline. The SES-CD is a composite of four features of endoscopic activity (presence and size of ulcers, extent of ulcerated surface, extent of affected and presence and type of narrowings or stenosis) in up to five ileocolonic segments (terminal ileum, right colon, transverse colon, sigmoid and left colon, and rectum). Each feature is scored on a scale from 0 to 3, giving segment subscores of 0 to 12 points and a total SES-CD range of 0-60, with a higher value indicating greater severity.

Percentage of participants with a decrease >=100 in CDAI from baseline.

Percentage of participants with a decrease >=30% in both SF and APS, with neither being greater than baseline.

Overall change in CD symptoms, as measured by the Patient Global Impression of Change (PGIC) from baseline to Weeks 2, 6, 12 and 52. PGIC measures overall change in Crohn's disease symptoms from "Much better" to "Much worse".

Overall severity in CD symptoms, as measured by the Patient Global Impression of Severity (PGIS) from baseline to Weeks 2, 6, 12 and 52. PGIS measures severity of Crohn's disease symptoms from "None" to "Very severe".

The average daily rating of general well-being in the past 7 days. Well-being is assessed on a scale of 0-4 with 0 indicating generally well and 4 indicating terrible.

Incidence and severity of AEs, including serious AEs, AEs leading to treatment discontinuation and AEs of special interest.

Fistulas will be assessed for draining or closed status, where closed fistulas will be assessed by the investigator as no longer draining.